1. Field of the Invention
The present invention relates generally to the fields of semiconductor manufacturing. More specifically, the present invention relates to a semiconductor wafer or glass substrate processing system comprising a double dual slot load lock and uses thereof.
2. Description of the Related Art
The need for greater throughput and yield in the manufacture of semiconductor devices has driven the development and use of more highly automated wafer processing machines. Also, the desire to minimize wafer particulate contamination during processing has led to the use of vacuum load locks and wafer transport mechanisms which operate in vacuum.
In continuous throughput systems, wafers must be introduced into the vacuum chamber through a load lock in order to prevent exposing the vacuum condition in the chamber to the air outside the chamber. When a wafer is to be loaded into the chamber, the inner closure means, such as a sealing plate, is activated to seal the inner side of the opening, and then the outer closure means, such as a sealing door, is opened. Next the door is opened, a wafer is inserted through the opening, and the door is again closed. The load lock chamber now containing the wafer is pumped down to contain an atmosphere compatible with the atmosphere in the processing vacuum chamber, and then the inner sealing plate is moved away from the opening to expose the wafer for processing in the main vacuum chamber. To increase the throughout, some systems employ two load lock chambers so that processing of wafers can continue uninterrupted by a delay caused by the need to open, empty, reload and re-equilibrate a single load lock chamber.
Despite the increased vacuum isolation, the state-of-the-art systems typically have difficulty providing commercially acceptable throughput for high vacuum processes. Presently, typical load lock chambers employ sliding or rotating valves to isolate a single wafer. Such load locks require a pumpdown cycle for each wafer processed and thus inhibit throughput. In addition, the load locks are typically in-line devices; that is, wafers pass in a straight line through the load lock. This substantially contributes to the overall width of the wafer processing machine. Furthermore, in the prior art designs, mechanical feedthroughs, which are used to transmit motion through a vacuum seal, have not been adequate to the task of simultaneously operating a load lock valve and indexing an internal wafer cassette.
Therefore, the prior art is deficient in the lack of effective system/means of processing substrates in a high throughput fashion and meanwhile minimizing particulate contamination during processing. Specifically, the prior art is deficient in the lack of a highly automated substrate processing system comprising double dual slot load locks constructed at one body. The present invention fulfills this long-standing need and desire in the art.